1. Field of the Invention
The present invention relates to a semiconductor device manufacturing method and a semiconductor device.
2. Description of the Related Art
As disclosed in JP 10-303098 A, a semiconductor device in this field is generally formed in the order of the following steps: a field oxide insulation film forming step in which a surface of a semiconductor substrate is subjected to local oxidization to form a field oxide insulation film, which grows thick along the surface of the semiconductor substrate, to divide the surface of the semiconductor substrate into a plurality of active regions; an electrode forming step in which an electrode film is formed on the surface of the semiconductor substrate, photoresist, which is applied to the surface of the electrode film by spin-coating, is exposed to light, and an unnecessary portion of the electrode film is etched and removed to form an electrode; and a resistor forming step in which a resistor film is formed on the surface of the semiconductor substrate, photoresist, which is applied to the surface of the resistor film by spin-coating, is exposed to light, and an unnecessary portion of the resistor film is etched and removed to form a resistor.
In these steps, a non-flat structure has been formed on the surface of the semiconductor substrate at the time of the electrode film formation in which a convex portion consists of the field oxide insulation film and a concave portion consists of the active region. The surface of the electrode film, which is formed on such a semiconductor substrate, is then also made uneven corresponding to the unevenness of the surface of the semiconductor substrate. Accordingly it is difficult to apply a photoresist so as to have a uniform thickness through spin-coating on the surface of such electrode film, and an uneven coating may consequently result.
More precisely, when the photoresist flows into a concave portion, which corresponds to an underlying active region, on the surface of the electrode film, the photoresist concentrates at the corner which is surrounded by side surface portions of the convex portion opposing to a rotation center in the surface of the semiconductor substrate for the spin-coating in a centrifugal force acting direction along the surface of the semiconductor substrate, and which locates in the forward side of the centrifugal force acting direction when the semiconductor substrate is seen in a plan view. A certain amount of concentrated photoresist, then, flows out of the concave portion. Uneven coating, as a result, may occur in a portion, on the surface of the electrode film, in the forward side of the corner along the centrifugal force acting direction.
In the above-mentioned semiconductor device manufacturing method, the uneven coating of photoresist on the surface of the electrode film lowers a dimension accuracy of the electrode, further affecting the subsequent resistor forming step, which leads to a lowering in the dimension accuracy of the resistor to the extent that the semiconductor device will not have desired characteristics.